Here is the story. Clan Donald (currently 117 individuals in the "red"
group) is the third "level" population, with all three form a compact branch
each on the R1a1 haplotype tree and each one has its common ancestor (MRCA).

The whole story is published in the November, 2009 issue of the Proceedings
of the Russian Academy of DNA Genealogy, vol. 2, No. 6, pp. 974-1099 (2009),
describing the whole family R1a1 haplotypes and their branches and TMRCAs.
It is a free download, however, it is in Russian:

The first level (in this context) is the "Old Scandinavian Branch", with a
common ancestor of 4100+/-700 ybp. It has DYS458=15, and YCAII=19-23.

The second level is the "Young Scandinavian Branch", with a CA of 1900+/-400
bp (another approach employing different haplotype trees gave 2550+/-330
ybp, which is overlapping with the first one within the margin of error, and
a third approach gave 2000 ybp). It has DYS458=15, and YCAII=19-21. It
consists of three sub-branches, each one having DYS458=15 and YCAII=19-21,
with TMRCAs of 1750+/-400, 1700+/-350, and 1250+/-350 ybp.

The third level is the Donald Clan, with DYS458=16, YCAII=19-21, and with a
CA of 825+/-120 ybp (if to count two quadruple mutations in two haplotypes),
of 775+/-110 (if to consider the two as one mutation each). It used to be
650 ybp for the earlier 60-80 haplotypes in the Clan, however, in 2008-2009
a number of haplotypes with multiple mutations were added, hence, TMRCA
moved down.

The old Scandinavian branch descended from the Russian Plain R1a1 common
ancestor of 4750+/-500 ybp. The young Scandinavian branch apparently
descended from a Central Asian R1a1 common ancestor of 2900 ybp, who in turn
descended from the Russian Plain R1a1 common ancestor of 4750 ybp (see
above).

The above-mentioned publication contains all 67-, 37-, and 25-marker
haplotypes trees for each "level" along with 67-marker base haplotypes for
each one and their sub-branches.

Anatole Klyosov

*****************

Andrew Mceachern:

Quote

"The same tests described above can be applied to this data. This analysis
confirms that the main R1a Clan Donald line is indeed the line of Somerled's
grandson "Donald the eponymous". The marker DYS458 appears, based on this
limited data, to distinguish MacDonald from MacAllister. One R1a participant
from Glencoe (whose line branches off from a brother of Lord John) also
shares 15 at DYS458. We now beleive that we have sufficient data to show
that the ancestral state was 15 at DYS458 and that the actual mutation
occured with the birth of Lord John himself, his father, or grandfather.
While this is not absolute proof, we consider it reliable at the 90% or
better level. DYS458 is a fairly fast marker, and we do see what are likely
back and parallel mutations. The number we see is quite accurately in accord
with the known mutation rate. The pattern of 11 at DYS442 and 12 at DYS438
is indicative of the name Alexander, though we do not know at all if this is
a universal diagnost!
ic"

"This subgroup contains the Clan Chiefs, indicated by a blue background:
Iain Godfrey Macdonald of Sleat, Ranald MacDonell of Glengarry, and Ranald
Alexander MacDonald of Clanranald. Allan Douglas MacDonald of Vallay,
Chieftain of the Vallay line, has a green background. Persons in this group
are possible descendants of Somerled, and are almost certainly of Norse
descent. The Group Modals line represents the most likely haplotype of John,
first Lord of the Isles (died 1386), and by implication of Somerled himself,
with the exception of DYS458. Because MacAlisters and one R1a1 person known
to be from Glencoe (whose R1a chiefly line began with a brother of Lord
John) are 15 at DYS458 we believe that Somerled was 15 at DYS458 and that
the mutation to 16 occured with the birth of Lord John himself, since all
his sons bear 16"